After upgrading Service Catalog, the login works fine.
However, the rest of the pages look like the screen below:
CA Service Catalog 17.1 and higher.
There are 2 branding templates CA_Technologies_R7 or CA_Technologies_R7_Full_Screen.
If this branding template is not present against the Business Unit that is being used, then such an issue happens.
To fix this (this can be done in the same Catalog screen as it shows up in the picture above)